1. Technical Field
This invention relates to a power switching device that automatically switches a load from a primary power source to a secondary power source upon interruption or loss of the primary power source.
More particularly, this invention relates to a transfer relay that provides a computer installation or other critical device the capability of accepting two sources of power, one primary and one backup, so that interruption to or loss of the primary power source causes the backup source to be automatically selected.
2. Description of Related Art
It is known in the art to provide a backup power supply, or secondary source of power, to maintain a computer in operation in the event that the primary power source fails or is interrupted.
This invention provides a transfer relay that is arranged to accept an electrical power input from each of two different and independent sources, one a primary source and the other a backup source, and to provide a single power output that serves to power a computer or other device needing uninterrupted operation. Upon the loss of power from the primary source, the relay automatically switches to the backup source and completes the transfer from one source to the other in less than one cycle in a fashion that is completely transparent to the load. The device returns to the primary power source as soon as it is restored.